In general, terminals connecting with an external device and the like are formed at predetermined portions of a wiring pattern in the final step of production of wiring circuit boards. For improved productivity of wiring circuit boards, plural wiring patterns are formed on a single metal sheet having a large area by a single process, and the patterns are divided to give respective wiring circuit boards. In many cases, terminals are formed on a wiring pattern on a wiring circuit board by an electroplating treatment. For this end, a multiplicity of partially completed wiring circuit boards are produced on a metal sheet. In the present specification, the “partially completed wiring circuit boards” means a semi-product in a stage before forming a terminal. Furthermore, a partially completed wiring circuit board assembly sheet wherein lead wires for electroplating are formed on a wiring pattern of each partially completed wiring circuit board is used. The lead wire for electroplating is formed to electrically feed a wiring pattern during an electroplating treatment.
FIG. 5 is a sectional view of a conventional partially completed wiring circuit board assembly sheet, wherein a partially completed wiring circuit board 10 is formed on a wiring circuit board forming area 1A of a metal sheet 1. The partially completed wiring circuit board 10 comprises a base insulating layer 2, a wiring pattern 3 and a cover insulating layer 4 laminated in this order, and further comprises an opening 4a for forming a terminal in the cover insulating layer 4. In the metal sheet 1, an area 1B for forming a lead wire for electroplating comprises a first insulating layer 12 formed by the same process as for the base insulating layer 2, a lead wire 13 for electroplating formed by the same process as for the wiring pattern 3 and connected to the wiring pattern 3, and a second insulating layer 14 formed by the same process as for the cover insulating layer 4, which are laminated in this order. FIG. 5 shows a lamination structure of an area 1B for forming a lead wire for electroplating and an area containing one wiring circuit board forming area 1A adjacent thereto. In practice, the metal sheet 1 comprises multiple wiring circuit board forming areas 1A, each of which has a partially completed wiring circuit board 10. Lead wires for electroplating 13 are connected to the wiring pattern 3 of each partially completed wiring circuit board 10.
As shown in JP-A-2002-20898, for example, such partially completed wiring circuit board assembly sheet is generally subjected to an electroplating treatment using a plating apparatus. A plating apparatus is equipped with a plating solution housing part that contains a plating solution, a sheet conveyor means that transports a partially completed wiring circuit board assembly sheet while being immersed in the plating solution in the plating solution housing part, and a power feeding means that supply electricity upon contact with a power feeding part of a lead wire for electroplating in a partially completed wiring circuit board assembly sheet. As shown in FIG. 6, a plating metal 5a is deposited on a wiring pattern 3 exposed from an opening 4a for forming a terminal in each of the multiple partially completed wiring circuit boards 10 to form a terminal (plated metal layer) 5, whereby a wiring circuit board 50 is completed.
In such a partially completed wiring circuit board assembly sheet, all conductive layers (wiring pattern 3, lead wire 13) on the metal sheet 1 are formed on an insulating layer (base insulating layer 2, first insulating layer 12) covering the surface of the metal sheet 1. In other words, these conductive layers are electrically insulated from the metal sheet 1. Therefore, when a power is fed via the lead wire 13 to the wiring pattern 3 to form a terminal 5 by an electroplating treatment, the metal sheet 1 is not electrified. As a result, in the wiring pattern 3, a plating metal 5a is deposited only on the part appearing from the opening 4a formed in a cover insulating layer 4.